The event's host and main public advocate since 1966, the veteran comedian was slated for a final appearance on this year's edition, entailing his traditional and typically emotional finale performance of "You'll Never Walk Alone." That changed suddenly a month ago, when a brief statement indicated Lewis had "completed his run" as national chairman of the MDA.

At this writing, neither party had given a reason for the early breakup, but Lewis -- who helped raise more than $1 billion for the MDA -- said he was planning his own press conference for the day after the telethon. Asked in July during a session with television critics about his telethon role this year, Lewis replied, "It's none of your business."

The show must go on, however, and it will ... with another major change. Usually an overnight Sunday-into-Monday event, the MDA Labor Day Telethon is being condensed into a six-hour prime-time telecast carried on more than 150 "Love Network" stations Sunday, Sept. 4. In most cases, talent from the respective station will appear in two local-origination segments each hour.

O'Dell has been pivotal in the MDA's "Make a Muscle, Make a Difference" campaign, and her involvement is deeply personal. She is the national ambassador for the organization's ALS division, dealing with the nerve-debilitating illness commonly known as Lou Gehrig's disease, of which O'Dell's mother died in 2008.

"It's really exciting, because it's so different," O'Dell says of the new telethon format. "Before, you'd have different performers in different time zones; sometimes you'd see them, and sometimes you wouldn't, because some of them would be on in the middle of the night. Now, because this is 6 p.m. to midnight in every time zone, you'll get to see everybody."

O'Dell has played a role in the MDA Telethon for several years, and she acknowledges Lewis' absence will generate "a different kind of feeling" during the fundraiser. "I remember watching him growing up as a little girl, and I think everybody knows about the telethon and his being such a big part of it. We're forever grateful for all he's done."

The MDA's mission remains, though, and O'Dell has evidence of its effectiveness: "After my mom was diagnosed with ALS, they were there for us every step of the way. I remember when Mom went into the emergency room, MDA people were on the phone, helping to guide me through what was happening. I know what great things they do and have done, every single year."